Electrical condenser



June 21, 1960 R. w. TWADDELL ETAL 2,942,167

ELECTRICAL coNDENsER Filed Jan. 6. 1958 United States Patent O 2,942,161 ELECTRICAL coNDENsER Russell W. Twaddell and Stephen E. Gregoire, Sidney, N.Y., assignors to Bendix Aviation Corporation, Sidney, N.Y., a corporation of Delaware Filed Jan. 6, 1958, Ser. No. 707,204

4 Claims. (Cl. 317-242) This invention relates to an electrical condenser, and more particularly relates to the combination of an electrical condenser having a pluraty of condenser sections of the laminated sheet type and a mounting device for such condenser.

The invention has among its objects the provision of a novel, improved condenser incorporating condenser sections ofthe laminated sheet type.

A further object of the invention lies in the provision of a condenser of the type above indicated which may be used throughout an extended range of temperatures from atmospheric Ito elevated temperatures.

Yet another object of the invention resides in theY provision of a condenser incorporating a novel mounting device therefor to maintain the capacity of the condenser substantially constant over such extended range of temperature.

A further object lies in the provision of an improved mounting device for a multiple-section condenser wherein the sections are of the laminated type, the mounting device being of simple rugged construction and preserving the condenser units against damage under conditions of severe vibration at elevated temperatures.

The above and further objects andnovel features of the invention will more fully appear from the following description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and are not intended as a definition of the limits of the invention. v

In the drawings, wherein like reference characters refer to like parts throughout the several views, Y

. Fig. l is a view in perspectivev of an assembled condenser and mounting device therefor made in accordance tially assembled condition, parts of the condenser being broken away to show the internal structure thereof;

Fig. 3 is a view in elevation of the condenser in a condition of assembly similar to that in Fig. 2, the view in Fig. 3 being taken from the point of view displaced 90 around the longitudinal axis of the pack from that in Fig. 2;

Fig. 4 is a fragmentary view in longitudinal section through the finally assembled condenser and mounting device therefor, the section being taken generally along the line 4 4 of Fig. 1, certain parts of the mounting device and of the condenser being broken away for clarity of illustration; and

Fig. 5 is a view in axial section through a bimetallic spring forming a portion of the condenser mounting device of the invention.

'I'he condenser and mounting device therefor of the present invention are illustrated herein in an embodiment designed to be incorporated in a high temperature igniter such as that disclosed and claimed in application Serial No. 707,388, tiled January 6, 1958 by Twaddell and Gregoire. A rectifier mounting device for such an igniter 2 is disclosed and claimed in application Serial No. 671,462, tiled July 12, 1957, and a circuit for such device is disclosed and claimed in application Serial No. 665,558, filed June 13, 1957, by Donald C. Loudon.

The igniter with which the condenser and mounting device therefor of the present invention may advantageously be used is designed to be'atixed to the housing of a jet or ram-jet engine. During periods in which the engine is running, the housing thereof reaches temperatureson the order of 700 or 800 F. so that the casing ofthe igniter and the components of the igniter circuit therein may reach temperatures as high as 500-F., despite the use of the inowing fuel as a coolant for the igniter. The heating and cooling of the condenser of the circuit, particularly if it is of the laminated pack type, tend to produce marked and undesirable variations in the capacity of the condenser when it is positioned in a container having fixed end walls. This arises from the subjection of the condenser to variable compressive forces directed endwise of the condenser stack. Further, since the igniter is attached to the housing of the engine, the component elements of the igniter are subjected to severe vibrations while the engine is running. The present invention is concerned with the provision of a condenser and a mounting device therefor such that the .condenser is protected against damage under such arduous operating conditions, and such that the capacity of the condenser is maintained substantially constant over the wide temperature range of its use.

The assembled condenser and the mounting container device therefor are shown in Fig. 1, where such combination is generally designated 10. The condenser, designated 11, is shown in an intermediate assembled stage in Figs. 2 and 3, and is shown nally assembled in the mounting container device in Fig. 4.

Such mounting container device, generally designated 12, is in the form of an elongated metallic housing or sheath of rectangular section, the sheath being provided within an end closure member 14 at the right thereof (Figs. l and 4) and an enclosure 15 at the left thereof (Fig. 4). The engine fuel circulated as a kcooling uid through the igniter, ows into housing 12 through a screened opening 20 and out of housing 12 through a similar opening, not shown. The mounting container is provided with elongated inverted U-shape channel members 16 aixed to opposite sides of the container. Menibers 16 form hangers by means of which the mounting is supported on the frame of the igniter as more fully shown in application Serial No. 707,388.

Condenser 11 includes a main container unit 18, at the left in Figs. 2, 3, and 4, and a voltage-doubling unit 27, shown at the right in such figures. Each of sections 18 and 27 includes a plurality of condenser sections of the laminated type wherein layers of electrically conducting foil are separated by interposed sheets of dielectric material such as paper. In the assembly shown, the voltagedoubling section 27 includes two condenser sections 31 connected in series by a wire 39 which forms one lead from the condenser assembly. The other, free end of the outer condenser section 31 is connected to ground through abroad electrically conductingtape 40. The free end of the inner condenser section 31 is connected to a second lead wire 37 from the condenser assembly and is also conmesme? chosen-to givefthe unit I8"`tl1'e desiredtotal" capacity. In practice, the sections will differ somewhat in capacity whenmade by, production methods. Accordingly,the capacitiesI ofi an appreciable-number olsections;are. de.-` termined; and the sections employedin mak'ihgunitl' are chosen so that1the ytotalcapacity closely approximates that desired. Thelhousing 12' is made of sucient length to receive the maximum number of condenser'seetions which' willLever be requiredto give thel desired totallca: pacity: In Fig. 4 housing 12` is shown containing a maximum number of condenser sections; end'fmember 1'5lying at the endofth'e housing.Y Whenless thansuch number, of'icondenser sections is` required, endlmcmber.` lwilllbe. positioned inwardly of fthe endofitlieA housing. 'lheevoltv age-doublingunit 27, inthe embodiment f.shown,fconsists4` ofthe two condenser sections` 31' which, are` carefully chosen; to have substantial-ly. the samepredetermined ca,-` pacity desired; Unit Z7 is positioned at `one .endY of unit` 18, as shown. v

The condenser sectionszlare assembled .in a stackand the1 described connections are., made. tosthe ,alternate :.pl'ates` thereof. The voltage-doubling sections4 31 connectedinY series by leadi39, are added to` thestack formedby sec.- tionsn 21. The free end of thev inner. section` 3l,is.con-- nectedto' one of the common leadsof unit 18,`;and.,they condenser leadf37`is connected` thereto, Fromtthethus. far assembled condenser, paclcthere extends theground leadi22at the maincondenser end, the, ground .lead .40 connected'to the freeend of ,theouter section-.Slaat thev voltage-doubling vend,andtlie.;two.condenser. Ileads37` and 39 from the sides of the ,housing ,.12.. adjacent thevoItage-Y doubling l end s of the pack.4`

The condenser, sectionsf 21-A of unit 18 a1'e, .iir,st held'-v tightly together in astack -byoneortmorelayersof iti-- sulati1'1g ,f1bricv 24,. 25, wrapped. abouty them, 4the-fabric..-I being lretanedby corner tapes 26., sidertapes2`8,` andgpe ripherally extending tapes-35.v The lead tape conductors extend -from the opposite tends ofthe ythusassembled `.and Wrappedfunit' ISL The condenser sections ,makinglup ,unit27 are'now as-: sembled and are .secured together by .insulating adhesive, tape suchA as shown at 32. Unit27 isfthenV `superimposed onfthfe stack forming unit `18, and ,the described electrical connections are made between it and unit :18: Axpluralityl of layers 34 of insulating `material are placedlonthe-outer, end offunit27 Unit 2.7 and layers,34are secured-.tounit 18 by longitudinally` extending insulating` adhesive `tapes.- 36.'

Edjclosuretmember 14 is.securedto-.housingflzras ,bybeing-3 ed'ge welded thereto. An annular, springg-member.` 421s' placed in the -housing ,in themanner shownimFig., 4, followingrwhich` a rigid,.metal pressure' orz plunger member 41,'` slidablyA tting within theV housing, nplaced inthe h`ousing. V A number oftthinlayers V33toftinsulatingj;

board,1 made for exampleof.Isomica arefthen.placed in the housing to lie4 againstthe innenfaceof member;

41'. The assembled. and,insulated condenser-.paolo isstheni telscoped Withinhousing 12 inthe manner.,showrrin4 Fig;-4. TheleadZZ 'from the main-,condenserzunit mayjbef or ,housing of the igniter.

and -`a second rigid, metal plunger -orJ presser. member. 41 Y,

is placed in the v.housing outwardly of such layers'f33. The

`assembly is completed byr placingend,,closurefmember .15j

inthe housing, pressingmember .15 ,axiallyfof the 1housing-l with a predetermined pressure,` and edge..weldinggclosure member 'to the housing 412.V In the illustrative embodiment shown, spring42 is placed .under. an zaxial, pressure of 800 lbs. with thercondensenassembly, at room-tem- The annular spring member 42 is dished as shown, being of a frusto-conical shape converging toward the body of the condenser. Spring `42 is made of bimetallic stock as shown in Fig. 5. The metallic component 45 lying radially inwardly of the spring member 42 has a higher coefficient of expansionE than the outer metallic .component 44.` Asatisfactorymember 421is one known perature, the springbeingheld.undenthis pressureffwhen;e`

end-"closure member 15is' welded 'to the housing.

as a Belleville bi-metal washer, made of a bimetallic stock soldunder-'the tradename."Wilco Thermo-Metal, High crease in length of housing 12. Member 42.is so chosen; as to maintain the. condenser sections.underfsubstantially constant compression throughout theV extended tempera-V ture range n which the igniter sused.

It will `be seen from the above that theY presentvv invention .provides-means for.mounting;aacondenser pack madei upof a..stackoisnperimposed laminated sections sofas4 to protect it `from injury. Further itholds -thesections un:- der. substantially thesame axial pressure, so thatthercapacity cime-condenser.doesnot vary appreciably, even.A though. parts; of the conden-ser'and. of the housing, therefforvary substantiallyin length upon. changes ofopera't-L ing temperature. l laminated `sheet type.,V condenser used., herein. includes condensers.. in which. the. various layer-s-Y are 1 formed sep.- alatelyy andthen; superimposed,` and also includescorr-- densers-.-form`ed by wrapping the-:various layers in. super,-` imposed relationship asy onza mandrel, withdrawing-tha mandrel, and fiattening the. wound .body` tok form .afgenerally, atsheet type condenser. havingV superimposed layers Although f onlyv one,.- embodiment of the.. inventionhasfi been`v illust-rated.- in thef accompanying.l drawings and` de.-` scribed fin the:foregoingspecification', itis lto be: expressly.'v understood.: thatV various echanges, such 'as-in thei relativei.' dimensions of the parts, materials used', .andl the like; as.

well as the` suggested wmanner' of use. of .the apparatusriof the invention, mayybeimade thereinwithout departing.'A

fromthe spirit and .scope-.of the invention as will now be apparenttothose skilled `inthe art. Thus, .for example, a plurality of pressure compensatingsprings'may beem'- p loyedsk in.pressure transmitting relationship with both endstof the condenser pack.;

What .isclairnediszf l. A condenscrtcomprising. arigid housing madeo material having a-z substantialwv coecient of expansion', fixed end members donf-the; oppositeends vof I the housing,`

afcondenserpack1 comprisinga plurality 'of sheets of" conducting material separated by layers of dielectric material', the condenserzpaclc-.being positionedinfthe housingwithmoneof the-'broad surfacesfof therpack parallel'` toi-and ini thrusting' relationship withone Aendv member ofl'thehousing, and'resilientl compressive means acting.

betvreeny ythe other-end" member ofthe housing' and the other broad surface ofk the pack, the resilient compressive meanscomprisingja .bimetallic spring which is` so positioned as to maintain the condenser pack. under a generally constant `compression through outan .extendcdrangc of.V temperature `2. A-.condenser asl deiined in claim 1, lwhe-rcinthe-condenser; pack expands vwith .risinggtemperature in` a direction.longitudinallygfofthe housing .to an: extent greater than;A lthe :elongation of Vthe housing; and.,wherein.;the"bilmetallic spring contracts in a direction axially of the It will be understood that the-term"- housing upon a rise in the temperature to which the condenser is subjected.

3. A condenser as defined in claim 2, wherein the bimetailie spring is of annular frusto-conical shape and is positioned generally coaxially of the condenser pack, and wherein the higher expansion component of the biinetallic spring is positioned radially inwardly of the lower expansion component.

4. A condenser comprising an elongated housing made of metal having substantial coeflcient of expansion, fixed end members on the opposite ends of the housing, a stack of condenser sections in the housing disposed longitudinally thereof, the sections comprising a plurality of sheets of electrically conducting material separated by layers of dielectric material, one end of the stack abutlfing a rst end member on the housing, a rigid plunger member slidably fitting within the housing in thrusting relationship to the other end of the stack, and resilient- Iy compressive means interposed between the other end men-Ther and said plunger member, the resiliently cornprcssivo means being a bimetallic spring of annular frusto-conical shape which is positioned generally coaxial of the stack, the higher expansion component of the bimetallic spring being positioned radially inwardly of the lower expansion component, whereby the bimetallic spring contracts in length in the direction axially of the housing as the temperature to which the condenser is subjected increases.

Reerences Cited in the le of this patent UNITED STATES PATENTS 2,229,694 Ducati Jan. 28, 1941 2,383,480 Heyman Aug, 28, 1945 2,799,816 Schwartz July 16, 1957 .FOREEGN PATENTS 460,909 Great Britain Feb. 9, 1937 

